The modern AR-15 style rifle platform is primarily comprised of MIL-SPEC (Military Specification) components, originally derived from the M16A1/A2, M4A1 and M16A4 variants. Platforms include semi-automatic, burst and full-automatic fire control versions, as well as a multitude of caliber configurations. Most modern AR-15 components have retained either MIL-SPEC adherence and/or a close resemblance thereof to the original 1956 Eugene Stoner and L. James Sullivan Armalite AR-15 design. All M16A1/A2, M4A1 and M16A4 variants retain absolute adherence to MIL-SPEC requirements, as these platforms are intended for applications in standardized military service. Nevertheless, since the original inception of the AR-15, M16/M4 variants, there remains an impractical design flaw which continues to be incorporated into every revision, improvement or reconfiguration of these platforms.
This flaw consists of an externally threaded barrel that requires a single-use crush washer to captivate and orient a muzzle device (e.g. flash hider, muzzle brake, compensator, suppressor, etc.). Installation and/or removal of a muzzle device requires the use of a wrench, and each new installation requires a new crush washer, in accordance with single use (MIL-SPEC) limitation. This design inherently impairs simple removal and/or replacement of muzzle devices. Furthermore, upon installation, the muzzle device must be accurately oriented and/or positioned to properly enable the flash hider pattern or provide correct recoil compensation direction. The muzzle device installer must rely solely on visual orientation during installation. If the device is tightened past an intended position, or requires reorientation, retarding the muzzle device away from a previous washer crush or collapse could render the crush washer unserviceable, as previous tension would be lost. Additionally, use of a crush washer may require cutting the washer from the barrel upon removal, as the crush action oftentimes deforms the washer around the threaded barrel, lower than the maximum thread diameter of the barrel, thus further impeding removal. Cosmetic damage to the barrel's finish can result because use of a tool to cut off the used crush washer is frequently required. Thus, it would be highly desirable to eliminate the need for a crush washer and a wrench to install a muzzle device on a firearm.
The aforementioned MIL-SPEC design utilizes a direct gas impingement system, which is comprised of a front sight base assembly that mitigates the redirection of ballistic gas pressure from barrel porting by means of a gas tube delivery to the BCG (Bolt Carrier Group to complete the direct gas impingement system cycle. The front sight base assembly also provides captivation of the gas tube and handguard cap, as well as integrated locations for the front sight post mechanism, bayonet lug, and sling swivel ring. Captivation of the front sight base to the barrel assembly is provided through two tapered pins that orientate and secure the front sight base to the barrel.
AR-style platforms that deviate from the original MIL-SPEC front sight base design must employ a gas block device to supplement the removal of the original front sight base. This gas block replacement is typically configured to slide onto the outer diameter of the barrel and over the barrel gas porting hole. Barrels are typically produced with a shouldered step diameter that is greater than that of the gas block inner diameter, to serve as a positioning stop. Once positioned up to this stop, the gas block is visually aligned on the barrel to ensure the gas tube, which is pinned to the gas block upon assembly, seats into the receiving face of the upper receiver. This orientation process is problematic because the gas tube may be slightly misaligned, permitting interference with the gas key on the BCG, thus allowing undesired friction and/or drag of the components. Likewise, and possibly more consequential, would be the compromised leaking of ballistic gas pressure between the gas tube and gas key, thus reducing the effectiveness of the direct gas impingement system cycle.
Affixing the gas block to the barrel within current industry standards is also problematic in that set screws are commonly used for this function. Considering set screws are limited to lateral pressure in one direction, their application creates a high probability of set screw force negating proper concentricity of gas block and barrel alignment. As such, a compromised seal between the gas block and barrel is often created, which negatively impacts the effectiveness of the direct gas impingement system cycle. Small set screws, typically ¼″ and smaller, are commonly used in gas block installations and are prone to overtightening, seizing, and stripping of the drive profile. It is not uncommon that seized or damaged set screws may require the gas block to be cut from the barrel to remove the gas block, which requires gas block replacement and can potentially damage the barrel. Furthermore, tightening the set screw onto the radial surface of the barrel can also negatively impact gas block alignment as the screws tightening rotational direction on the radial surface can cause the gas block to twist upon installation. After a gas block has been tightened to a barrel in a misaligned position, the gas block will often repeat the misalignment when attempts are made to re-orient it because the barrel has usually been scored by the previous set screw tightening and orientation attempt.
One common approach to reduce gas block twist or misalignment during installation is to provide a flat surface, pocket depression(s), or dimple(s) on the barrel's outer diameter for set screw nesting. However, the overtightening, seizing and/or stripping of the set screw drive profile remains a problematic condition, as does the unfavorable conditions regarding gas block distorting and subsequent ballistic gas pressure compromise. As there exists no standardized pattern or set screw spacing within the firearms industry, barrel alterations regarding pocket depressions or dimples may cause mismatched conditions, including inappropriate positioning on commercially available, non-standardized gas blocks.
Additionally, misaligned gas blocks can also prevent appropriate handguard installation because internal profiles of handguards tend to be limited in space and require a close and parallel and/or perpendicular alignment with the gas block. When a gas block's orientation prohibits handguard installation, the gas block must be reoriented, further compounding the previously stated detrimental conditions.
Finally, the current industry standard for gas block captivation can provide less than adequate mechanical holding force when hardware (i.e. set screws) has been compromised. This condition is further exacerbated when the gas block is exposed to ballistic gas pressures outside original MIL-SPEC design parameters. Gas block movement and subsequent loss of operating gas pressure commonly occurs under these circumstances.
The aforementioned MIL-SPEC design utilizes an integrated handguard assembly, also referred to as a forearm, which is generally replaced on rifle platforms that deviate from the original MIL-SPEC design. Most prevalent replacement handguard styles employ a float design (commonly referred to as a free float handguard) in which the only point of contact between the firearm and the handguard is at the barrel nut that secures the barrel to the upper receiver. Most designs employ an extended barrel nut that secures the barrel to the upper receiver, thus serving as a mounting base for the handguard. Handguard ends are commonly slotted and supplied with several clamping screws that apply clamping pressure around the barrel nut with a slotted clamp force to captivate the handguard around the barrel nut. The slotted clamp force design is problematic because clamping forces are not applied concentrically around the barrel nut's base, thus distorting and often seizing the handguard around the barrel nut, which impedes removal or adjustment. This condition also negatively alters handguard to barrel alignment. The extended design of the barrel nut also adds additional weight to the firearm.
Another type of handguard captivation utilizes a sleeved-coupling system that employs a threaded locking ring to secure the handguard body to a barrel nut. A primary shortcoming of this design entails the alignment of the barrel nut to a proper orientation in relationship to the upper receiver gas tube port. Overtightening often occurs when attempting proper alignment, or a shim may be required to time thread engagement with port alignment. This design commonly requires a special tool, such as a spanner wrench, to install or remove the handguard; which further complicates installation, removal, or adjustment of the handguard.
An additional mounting design exists that utilizes a laterally bolted system, which is mounted upon a handguard base, which then is mounted to the upper receiver. While this design offers more consistent and evenly dispersed clamping force, the design does not address handguard alignment and permits misaligned handguard installation. When a handguard is misaligned, it is often difficult to access the driving profile of the hardware to secure the handguard.
With any conventional handguard design, the inability to repeatably ensure a specified alignment creates further complications when an optical aid or sighting device (e.g. flip-up sight post, laser sight, etc.) is mounted to the handguard. When the handguard cannot be repeatably removed and reattached to a firearm in a specified alignment, sighting devices must be recalibrated or zeroed once a handguard installation has been compromised or altered. While many prior art handguard mounting designs exist, including other variations not specifically discussed, existing handguard designs do not ensure rigid application, repeatable installation, control of proper alignment, and ease of use.
Therefore, a need exists for a new and improved firearm having an orientation element that releasably secures a muzzle device to the firearm in a specified orientation without requiring the use of tools or a single-use crush washer. A need also exists for a firearm having a gas block with orienting features that ensures accurate orientation and positioning of the gas block on the firearm's barrel. A need also exists for a firearm having a floating handguard that can be repeatably secured to the firearm in a specified orientation to eliminate the need to recalibrate a sighting device attached to the handguard if the handguard is removed and reattached. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the firearm according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of having an orientation element that releasably secures a muzzle device to the firearm in a specified orientation without requiring the use of tools or a single-use crush washer. The apparatus has also been developed for the purpose of providing a gas block with orienting features that ensures accurate orientation and positioning of the gas block on the firearm's barrel. The apparatus has also been developed for the purpose of providing a floating handguard that can be repeatably secured to the firearm in a specified orientation to eliminate the need to recalibrate a sighting device attached to the handguard if the handguard is removed and reattached.